Peter Cuthbertson runs theCentre for Crime Prevention. He was the Conservative Candidate for Darlington in 2015 and for Darlington and Durham Police and Crime Commissioner in 2016.

When Michael Howard became Home Secretary the first thing civil servants did was warn him against even trying: “I was shown charts which showed crime rising inexorably and [told] that there is nothing you can do about it”.

Howard could have been forgiven for taking the same view himself after four decades of rising crime. Instead, he pursued a brave strategy of sending far more criminals to prison. It’s a strategy most of his successors have continued and none have reversed. He faced down endless fatalism from the Home Office and sneers from the media, most criminologists and the liberal left – and he succeeded.

As Howard said time and again, prison works. When he became Home Secretary, 40 per cent of households would report they had been victims of crime in the previous year. Now, 15 per cent do.

It’s not as familiar a story as it should be – and its lessons are too easily minimised. I was disappointed when Michael Tomlinson recently wrote for ConservativeHome arguing that “if your measure of success is the number of people who come out of prison a reformed character, ready to re-join society and sin no more, then at present prison does not work.”

There is nothing wrong with wanting more rehabilitation of criminals. But the only way it makes sense to say “prison does not work” is if one believes that rehabilitation rates are the only measure of success and ignore massive reductions in, well, actual crime!

If the average criminal commits 140 crimes a year, as the Home Office once found, then four years in prison prevents 560 offences against individuals and families outside prison – even if he eventually reoffends. One can ignore this incapacitation effect and argue that all that matters is whether the criminal is a reformed character four years later. But this attitude means callously ignoring the fate of every one of those victims of those 560 crimes. Crime rates matter, too.

The graph above shows that, since 1981, every extra criminal in prison was associated with an average of 161 fewer crimes a year – strikingly similar to the 140 crimes a year the Home Office estimated. This was a statistically significant result (p = 0.00002) and the correlation between putting more criminals in prison and falling crime was 0.76.

Put in prison tens of thousands more criminals, each of them otherwise committing an average of 140 to 161 offences a year, and fewer people fall victim to crime. Since Michael Howard we have seen many millions fewer become victims.

Just as important, this “prison does not work” argument ignores the similar (and often worse) reoffending rates for the alternatives to prison. It’s criminals who have a high reoffending rate, whether or not they go to prison.

By far the biggest determinant of whether someone reoffends is their criminal history. 44.7 per cent of criminals with 11 or more previous convictions to their name reoffend within a year. This is six times as high as those with no previous convictions (7.5 per cent).

Prisoners are disproportionately the most hardened and prolific criminals, as one would expect. Prison only ever compares badly for reoffending rates when one fails to account for this difference.

In the year ending September 2016, those hardened criminals with 15 or more previous offences were more than three times as likely to receive a prison sentence as a community sentence, fine or suspended sentence respectively. Prison was five times as likely for those with more than 60 previous convictions.

So prisons are dealing with a much tougher cohort. Even so, there is no reason to single out prisons for failing to rehabilitate. Fines, community sentences, suspended sentences have a similar or worse reoffending rate than all but the shortest prison sentences.

If one wishes to single prisons out, it should be by noting that those sent to prison for two years or more have a lower reoffending rate than non-custodial alternatives, despite dealing with much tougher customers. The longer the prison sentence, the lower the reoffending rate, as this Ministry of Justice graph makes clear.

The police officer blogger Inspector Gadget offers one explanation for why longer sentences have such a good record of turning people straight:

“If you have someone in custody who is facing a proper sentence, they change. Suddenly, they want to talk to you and grass their mates up, suddenly they want a lawyer, suddenly they need consultations for hours, suddenly they are in tears and want to see their family, suddenly they are asking their missus to bring in their favourite pictures of the kids. They are calling you Sir and smoking 20 fags an hour. When you have the same men in for a summary-only offence (only triable before the magistrates, with no custodial sentences beyond six months and terms that long an extreme rarity), they’re sneering and swaggering and hoping the police officers and their families all die of cancer.”

The obvious implication is that Michael Howard was right to begin the process by which the prison population has doubled. As we see on everything from interwar rearmament to the Miners’ Strike, the left is great at rewriting history, however weak its case. We seem to be weak at simply writing it. Prison works – and Michael Howard’s legacy is as great a legacy as the Right to Buy, trade union reform and deficit reduction.

By hailing these economic achievements but underplaying other great conservative achievements like slashing crime, we risk unwittingly playing to the old stereotype of Conservatives caring only about money and not our wider society. This is particularly true for crime, which disproportionally affects those on low incomes. If the term ‘progressive’ means anything other than “Nick Clegg would agree!”, it means policies that help most those with least. This could make Michael Howard the most progressive politician in living memory. Conservatives should remember and honour this remarkable legacy.